Electric-circuit controller.



H. W, LEONARD. ELECTRIC 0111mm CONTROLLER.

APPLICATION IILED NOV. 7, 1907. v 929,609. Patentqd July 27, 1909.

WITNESSES INVENTOF 4" J34, AITOHNEXS.

UN ITEI) STATES PATENT OFFICE.

ARRY WARD LEONARD, OF BRONXVILLE, NEW YORK.

ELECTRIC-CIRCUIT CONTROLLER.

Original application filed June 1, 1903, Serial No. 159,528. Divided andthis application filed November 7, 1907.

' Specification of Letters Patent.

Patented July 27, 1909.

Serial No. 401,056.

To all 'wlzom it may concern:

Be it known that I, HARRY WARD LEON- ARI), a citizen of the UnitedStates, residing at Bronxville, in the county of Westchester and Stateof New York, have invented certain new and useful Improvements inElectric-Circuit Controllers, of which the following i a full, clear,and exact specification.

My invention relates to devices such as are employed to cause theautomatic release of the movable levers of switches, rheostats,&c.,under abnormal conditions, and thus open, or affect the conditionsin, an electric CllCUllL The present ap lication is a; division of mycopending app ication filed June 1, 1903, Serial Number 159,528, andwhich was renewed June 3, 1907, Serial Number 377,046.

The principal object of my invention is to produce an automatic releasewhich will be simple, reliable, constant, compact, cheap to manufacture,economical in operation, and easily and cheaply kept in perfectoperative condition in combination with circuit controlling devices asindicated herein.

In carrying my invention into effect I provide in my preferred form, amechanical lock ing device for holding a. switch or rheostat lever inthe desired operative position against spring or other tension, whilethe circuit to be controlled or a controlling circuit remains.

normal. This switch or rheostat lever is released to affect the circuitto be controlled when the condition of the circuit becomes abnormal andthe release is effected by an 'eleotro-responsive device which respondsautomatically to abnormal changes in a cir-, cuit. This electro-re'sonsive device preferahly (-onsists of'a so enoid having a verticallymoving core which is arranged to trip the latch. The core of thesolenoid in the preferred. arrangement, is normally held up againstgravity by the magnetism, and upon the occurrence of no-voltage orunderload the core will drop and trip the latch. In other forms the coremay be held down by magnetism against s 'n'ing pressure and upon theoccurrence of abnormal conditions in the circuit the magnetism will failto hold the coro whereupon the core will be driven upand to trip thelatch. These arrangements may be combined with automatic overloadswitches, employed in conjunction with a rheostat. In certain forms ofthe underload tomatically electro-responsive device, the core is movedto its normal operative position upward a ainst gravity or in somedirection against sprin or equivalent pressure during the initiamovement of the rheostat or switch lever. This movement of the coremaybe accomplished in several ways, either niechanically orelectrically, and the object of this movement is to permit the latch toreturn to the locking position and in some instances to place the corein position to instantly trip the latch, even before the opera-.

Heretofore in motor startingrheos'tats equipped with an automaticundcrload release, such automatic device was in the form of a magnet thekeeper ofwhich is attached to the switch arm. This form of automaticrelease depends upon the magnetism of the magnet to hold the keeper andarm against the action of aspring, so that when the mag netism of thismagnet fails the kee er is released and the spring moves the ever autothe desired position. There are severa objectiona do features to such anarrangement, which objectionable features I am able to avoid by myinvention. First. The magnetic pull of such a magnet depends verylargely upon the perfection of magnetic contact of the keeper. It thekeeper be nicely fitted the residual magnetism is quite strong so thatfrequently the automatic release fails to act when it should do so uponthe failure of current because the residual magnetism. and the frictionof the switch lever on the contacts are too great for the springto'overcome them. This residual magnetism is especially troublesome whenthe holding magnet is in the field circuit of a motor and the armatureand field are kept in aolosod circuit, for in such a case the gradualslowing down of the motor causes an (ex-- tremely slow and gradualdecrease of the current in the magnet to zero, which makes the residualmagnetism quite considerable in amount. To overcome this residualmagnetism it becomes necessary to use a very high grade expensivequality of iron in the magnetic circuit of the magnet and also to make aslight magnetic gap where the keeper makes -mechanical contact with thepoles ofthe magnet. This is frequently done by copper plating or tinningthis surface to a sufficient extent to create the desirable magneticgap. But any slight variation in this magnetic gap makes a greatdifference in the it is sometimes desired to have this magnet in serieswith the shunt field winding of the motor and here again anotherdliiiculty is met with as the current in the shunt field winding of themotor of a certain definite voltage and horsepower, is variable over anextremely wide range depending upon the particular make. ln commonpractice this variation would have a range of from 1 to 4. Hence withthe construction described, the magnetic pull would vary over a verywide range and the maker of such motor starters with automatic releasecan'- not tell in advance what magnetic )ull will be met with inpractice and is obliged to make the -magnet very much larger than reallynecessary in order to secure enough ampere turns to get the requiredpulleven with the minimum amperes met with in practice and yet the magnetmust be wound with a wire sulliciently large so not to have it overheatwith a current say 4 times as much as the minimum. All of thesedifficulties I avoid by means of my invention.

Instead of holding the spring actuated arm by means of magnetismproduced by the shuntfield current of the motor or other current, I holdthe arm in my preferred form by means of the mechanical latch. By theemployment of a mechanical latch, I am able to use as stiff a spring asdesired, so that no difficulties arise due to the friction which thespring may have to overcome in moving the arm after the latch isreleased. The latch is released by means of a definite hammer blow dueto the movement of a certain mass under the action of a constant forcepreferably gravity, although I may use a spring or other form of forceproducing device instead of gravity. I prefer however to use a freelyfalling weight falling a definite distance and therefore giving apredetcrminable and constant blow to open the latch when itoper ates.This weight is preferably in the form of a magnetic plunger which isnormally held up by a magnetic pull and which fails when the currentfalls below a certain amount and delivers a blow to open the latch. As Ionly have to sustain by means of the magnetism a weight, the weight ofwhich is very slight as compared with the pull oi the spring on thekeeper in the former type, I can readily introduce a considerable airgap in my magnetic circuit and yet have a magnet which is smaller,cheaper, and in every way better and more reliable than the former typedescribed above. For example, I find .turns of a. certain size wire areamply su'fiicient for the magnet in the field circuit when 350 turns arenecessary in .the former type, and of course the first cost, space, andthe energy required are proportional to these figures.

T he latch may be'so designed that its center of gravity is so disposedrelatively to its pivot that the action of gravity tends to keep it inthe locking position, as shown in Fig. 2 of my original application, ora light spring may be used tending constantly to 'keep it in thatposition, 'or the magnetic pull of the plunger may tend to keep thelatch in that position, or the shape of the latch may be such-as to haveit tend to remain in the locking position.

I prefer to have the solenoid iron-clad and closed at the top by iron,so that when the plunger is at the top of its movement the iron of theplunger is almost in contact with the iron of the solenoid, beingpreferably separated by a thin film of non-magnetic material, so as tosuiliciently reduce the residual magnetism effect.

My original application disclosed several forms and arrangements ofvarious embodiments of my'invention but the present apor a current dueto an independent circuit across the line, and I may arrange anotherplunger so that it is mechanically attached to the first one and a coilin series with the armature which acting on the second plunger whenexcessive current passes through the armature, pulls the second plungerand 'con sequently the first plunger to release the latch. Thus I get novoltage and overload automatic protection with a single arm, a singlelatch and a very compact form of magnet windings. f

When the air gap is large the cross section of the iron is not'important, and by making the cross section very small, economy in costand size of both the lifting coil and theholding coil is effected. Itherefore reduce the size of the plunger in practice to about onequarterof an inch in diameter. This results in a further advantage inthat thedensity of the lines of force is increased at the magneticholding/surface which gives a better result for the same number ofampere turns. WVith this reduced lunger additional weight may besupplied 1; iereto exterior to the coil or at the bottom of the plunger.

Some forms of my invention are illustrated in the accompanying drawingsin which Figure 1 is a diagram showing one form employed in connectionwith a shunt wound electric motor; and Fig. 2 is a diagram of amodification.

The mechanism will preferably be mounted upon the usual base ofinsulating material, carrying the resistance steps and circuitconnections on its underside and the contact buttons act the resistancesteps on its upper side or face.

B is the usual pivoted switch arm provided with an operating handleb.and a spring I) tending to return the arm to the initial or startingposition. v

L designates a latch pivotally mounted on the base plate andprovidedwith a tri ping arm Z. The latch and tripping arm s ould be soshaped and proportioned in weight that it will always assume thelatching position when free, and such an. arrangement will be suitablewhere the apparatus is designed to be placed vertically; but since theapparatus will not always be hung sufiiciently accurately, or since itmay be desired to place it in a horizontal position, I referably providethe latch with avery lig t spring Z which tends to return the latch tothe locking osition. Latch L engages a pin b on arm to hold the arm inits final position. An ironclad solenoid as shown and described inFig. 6of my ori inal application, may be provided, and the core thereofarranged as described so that when the current through the solenoidfails or decreases abnormally the magnetism will be insufficient to holdthe core in its raised position and hence the core will drop, andthrough the head on rod .9 impart a blow to the tripping arm of thelatch, thereby releasing the switch arm B and permitting the spring I)to return the switch arm to the initial or starting position. \Vith my,preferred form of invention I provide a mechanical device whereby whenthe contact arm is moving from the open circuit to the closed circuitposition, the core will be held in a sulliciently elevated position topermit the magnetic pull to hold the same or lift it farther to its fullelevated position. Arrangements for accomplishing the elevation of thecore are illustrated in the accompanying figures in addition to otherfeatures.

Referring to Fig. 1, M represents a shunt wound electric motor connectedacross a cir cuit through a starting rheostat. The holding or no-voltagecoil is indicated at U acting upon the core C and connected between thefirst contact of the rheostat and the motor field winding. In Fig. 1,two windings are employed to represent respectively the over-- load andunderload, and the cores are raised to the operative position either byhand or by an arm on the rheostat switch, both an rangements beingshown. In this construction, the under-load coil U is placed above theWill hold the cores elevated as the switch is instead moved toward thefinal position. of employing arm B and disk 8, the cores maybe elevatedby hand by means oi a knob s at the lower extension of rod 8. In suchcase the operator will raise the cores with one hand as he starts switchB forward with the other hand. The tripping arm I of the latch extendsbetween the two cores in position to be struck by the upper core whenboth cores descend. Under normal conditions the pull of coilU will holdthe cores elevated against gravity and against the pull of coil 0, butupon the occurrence of no voltage or an abnormal decrease of current,coil U will have insufficient pull to hold the cores against gravitywhereupon. they will fall and deliver a blow to and thereby tripthelatch. Upon the occurrence of a predetermined overload, the pull of coil0 will increase sullicicntlyto overcome the pull of coil U, and thecores will be drawn downward and trip the latch. .it will thus be seenthat by the provision of an extremely simple and compact device, i. (2.,a single arm, a single latch and a very simple, cheap and compactsolenoid, I secure both. no-voltage and overload release in a mosteffective and reliable manner. it will be noted that the circuitconnectim'is extend. from one side of the line through the arm B, which,when closed on the first resistance contact will cause the current topass through the starting resistance thence through overload coil O andthrough the motor armature to the other side of the line; also, a shuntcircuit extends from the initial contact through the holding orno-voltagcv coil U and the motor .[icld winding to the other side of theline. It will be noted that the motor armature, overload coil, holdingcoil and motor lield winding are in a permanently closed circuit. "v"!hen from any cause the latch is tripped by the falling of the cores ofthe solenoids, the arm B will engage the disk 3 upon the return of therheostat arm to the initial position and mechanically raise the coresand rod 8 to the position shown in the drawing. Consequently, upon againstarting the motor, the coil U will be energized and hold the cores inthe raised position as above referred to. The running position is shownin full line in the figure with all of the star ng resistance removedfrom the circuit, and the off-position fis indicated in dotted lines. iv

In Fig. 2 I have shown another construction in which the core or plungeris raised to operative position mechanically. Here the "switch arm B isprovided with an angular extension B, the pivotal point being soarranged relatively to the plunger that when the switch returns to itsextreme inoperative position at the left, 'the extension B will raisethe plunger to the position iniwhich it is illustrated. When switch B ismoved forward and the circuit closed, the plunger will still be withinthe no-voltage or holding coil H, and it will now be held by magnetismas switch B is moved toward the final position.

The holdingcoilHis'here connected in series with the field winding-oimotor M as in the} other arrangements and the release is effected in thesame way.

While I have shown and described certain. forms of my invention, it willbe understood that the invention is capable of embodiments in otherforms of construction, and I do not wishto be limited in the scopethereof except as indicated by the following claims.

Having'thus described my invention, I declare that what I claim as newand desire to secure by Letters Patent, is, I

1. The combination of a circuit controller having a movable element forvarying a resistance, said element being adapted to be restrained in acertain position, an electroresponsive device having an independentlymovable magnetic mass functionally related to the said element to effectthe opening of the circuit by the movement of said element, andmechanical means operative only when said controller is in a positionother than its normal operative position for moving said mass against aconstantly acting force.

2. The combination with a switch, of a mechanical device for holding itin a definite position, an electromagnetic device having a movablepartheld by said electromagnetic device against the action of a forcetending to move it whereby when the magnetism of said electromagneticdevice falls below a certainstrength, the said movable part will moveunder the action of said force and deliver a blow and cause the releaseof said mechanical holding device, and auxiliary mechanical means formoving said movable part to its normal operating position 'Thecombination of a spring actuated switch, mechanical restraining meanstherefor, a magnetic mass which falls under the action of gravity torelease said restraining means upon abnormal conditions of the circuit,mechanicalmmeans for automatically raising said mass to its operativeposition? and for retaining said mass in its operative position vwherebythe electric energy required for holding said mass in its operativeposition is materially less than the electric energy employed to raisesaid mass.

4. The combination of a circuit controller,

mechanical restraining means for holding said controller in a certainposition, a normally restrained mass which when released moves under theaction of a force and delivers a hammer blow to release the mechanicalrestraining means, and auxiliary mechanical means acting only when saidcircuit controller is in a position other than its normally re strainedposition whereby the saldmass' is moved to its normal positlon.

5. The combination of an electric motor, a

circuit-controller, protective means automatically responding to causethe opening of the circuit upon the occurrence of one abnormal conditionand to cause the opening oi'the v a circuit upon the occurrence of adifierentabnormal condition, and auxiliary mechanical means controlledby said circuit controller for setting part of said protective meanswhen said controller is placed in a certain position other than itsnormal operating position.

6.. The combination of an electric motor, a circuit controller,protective means automatically responding to afiect saidcontroller uponthe occurrence of one abnormal condition and .to aiiect said controllerupon the occurrence of a difierent abnormal condition, andauxiliarymechanical means controlled by said cireuitcontroller'for setting partof said protective means when said controller is placed in a positionother than its normal operating position.

7. The combination of a circuit controller, electroresponsive} meansresponsive tominimum conditions'and to maximum conditions,

and auxiliary mechanical means for moving to its normal position againsta' constantly acting force. 7

8. The combination of an electric motor, a

resistance havingsammovable element for in circuit varying the amount,of resistance and adapted to be restrained in the resistance all outposition, a magnetic mass functionally related to said device,

the action of a-force, and mechanical means for moving said mass to itsoperative posi tion by movement ofv said element.

9. The combination of an electric motor, a

resistance having a movable element for varying the amount ofres1stance-mc1rcu1t and adapted to be restrained the resist I a magneticmass tune tionall-y relatedto said element, electromagg ance 'all outposition,

- a movable element of said first named means o el'ectromagnetic meansfor retaining said device against.

said-means being operative while saiddevice is being moved to itsinitial position.

10. The combination of an electric motor,

a resistance having a movable device for varying the amount ofresistance 1n circult and adapted to be restrained n the reslst- '5 anceall out position, a magnetic mass functional'." related to said device,electromagnetic means for retaining said mass in a position againsttheiaction of a force, mechanical means operative only when said deviceis 111 a positiomother than its resistance all out posiof a mechanicaldev'ce for holding it in a definite position,'an electromagnetic devicehaving a movable part held by said electr') m agnctic deviceagainst theaction of a forr e tending to move it whereby when the our- 2 rent whichenergizes said electromagnetic device falls'below a certain strength thesaid lovable part will move under the action of said force and deliver ablow and cause the an electromagnetic device responsive to abrelease ofsaid mechanical holding device,

and auxiliary mechanical means acting only 'while the switch lever is ina position other than its normal operating position for moving saidmovable part to its held position.

12. The combination with an electric-mo- I tor, ofa circuit controllingswitch, means for moving said switch, mechanical restraining means forholding said switch, an automatic device having a movable part normallyrestrained by magnetism and which automatically operates when theelectromotive force of the circuit falls below a certain amount torelease, sald mechanical restrain ng means and p'ern'ntting the movementof said switch by its actuating means, and auxiliary me- 40 c a nicalmeans controlled by said switch for placing the said movable part in itsnormally restrained position. i

13. The combination of a circuit controlling swite'h, means tending tomove said I switch automatically, mechanical restraining means forholding the switch in a certain position, an electromagnetic devicehaving a magnetic mass normally held up against the action of gravityand which under abnormal conditions of the circuit falls and delivers a15. The combination of a circuit controlling switch having means tendingto move the switch in one direction, a mechanical restraining device forholding said switch in a certain position, an electromagnetic devicehaving a movable part for releasing said mechanical restraining deviceunder abnormal conditions of the circuit, and auxiliary mechanical.means controlled by said switch for placing the movable part of saidelectromagnetic device in operative position.

16. The combination of a circuit controlling switch, mechanicalrestraining means for holding saidswitch in a fixed position, anelectromagnetic device responsive to abnormal conditions in the circuitfor releasing said mechanical restraining means, and auxiliarymechanical means controlled by said switch for placing the movable partof said electromagnetic device'in operative position.

17. The combination with a circuit controlling switch, mechanicalrestraining means for holding said switch in a fixed position,

normal conditions of the circuit for releasing 'said mechanicalrestraining means, the movable part of said electromagnetic device bcingsubjected to a continually acting force in one direction, and auxiliarymechanical means for moving said movable part against said continuallyacting force to place the same in operative position.

18. The combination of a circuit controlling switch, mechanicalrestraining means for holding said switch in a fixed position,

an electromagnetic device responsive to abnormal conditions in thecircuit for relcasind said mechanical restraining means, the movablepart of said electromagnetic device being operated by gravity, ,andauxiliary mechanical means controlled by said switch for movingsaidmovable part against the force of gravity to place the same in operativeposition.

19. The combination of a motor having a field winding energized indeendently of its armature current, a mova le circuit controlling elementin series with one element of the motor, means for restraining saidelement against a constantly acting force,a mass ada ted to be moved todeliver a blow to effect t 1e release of said restraining means,electroresponsive means for retaining said' mass in its operativeposition, and mechanical means for moving said mass to said operativeosition.

20. T 1e cdmbination of a supply circuit,

' two movable magnetic masses mechanically connected together, twoelectro-responsive windings acting upon 'said masses respec' tively, oneof said windings being responsive to excessive current and the other ofsaid windings being responsive to a different abnormal condition, eachof said windings producing a magnetic field substantially independent ofthat produced by the other, and protective means controlled by themovement of said masses.

21. \The combination of an electric-motor,

and protective means comprising a no-voltage protective winding and anover-load protective winding, each of said windings having itsownrespective magnetic mass under the influence of its magnetic field I10 whereby the magnetic pull of each is substantially independent ofthat of the other and the masses being mechanically connected together.

22. The combination of an electric motor,

and protective means comprising a movable part adapted to be movedfreely under the action of gravity and deliver a hammer-like blow tocause the operation of the protective means and also adapted to bemoved. magnetically, two controlling electro-responsive windings actingupon said part, one of said windings belng in series with the motorarmature and the other of said windings being energized independently ofthe motor armature current.

23. The-combination of an electric motor, and protective meanscomprising two electro-magnetic windings, one of said windings being inseries with the motor armature and the other in parallel with the motorarmature, a movable device controlled by said windings and adaptedtodeliver a hammerlike blow to cause the protective movement of theprotective means upon the occurrence of an abnormal condition, andauxiliary means for movingsaid device.

'24. The combination of a circuit controller having a movable element;two windings, one responsive to minimum energy con- 40 ditions and theother responsive to maximum energy conditions in a circuit, each of saidWindings'developing a magnetic field sub stantially independent of thatproduced by the other, a magnetic element controlled by said windingsand normally magnetically restramed by magnetism against a constantlyacting force and adapted when released to. move under the action of saidforce to effect the automatic movement of said element.

25. The combination of a circuit controller having a movable element,two windings, one responsive to minimum energy conditlons and the otherresponsive to maximum energy conditions in a circuit, a magnetic masscontrolled by said windings and normally magnetically restrained bymagnetism against a constantly acting force and adapted when released tomove under the action of said force to effect the automatic tioller,meansfor causing said controller to be automatically responsive toabnormal conditions of the circuit comprising two electro-fresponsivewindings, a magnetic element acted upon by said windings and normallyrestrained by magnetism against a constantly acting force, and auxiliarymeans for automatically moving said element against the action. of saidforce to itemstrained position.

27. The combination of a spring actuated switch, mechanical restrainingmeans therefor, a movable magnetic element adapted to be moved from acertain position to deliver a blow to efiectthe release of said means,two electroresponsive windings for automatically controlling themovement of said element, and auxiliary means for automatically movingsaid element to said certain position.

28. The combination of an automatic switch, means for causing saidswitch to be automatically moved to a protective posi tion comprising amagnetic element, two con-, trolling windings for said ele1nent,. oneadapted to normally hold said element in its restrained position and theother winding adapted to counteract the effect of the first windingunder certain conditions and thereby eifect the movement of saidelement, and means depending upon the movement of said switch for movingsaid mass to its nor mally restrained position.

29. The combination with a switch, of a mechanical device for holding itin a definite position, an electro-magnetic device having a movable partheld by said electro-inagnetic device against the action of a forcetending to move it whereby when the magnetism of said electro-niagneticdevice falls below a certain strength, the said movable part will moveunder the action of said force and cause the release of said mechanicalholding device, and auxiliary mechanical means for moving said movablepart to its normal operating position.

30. The combination of an automatic switch, means for causing saidswitch to be automatically moved to a protective position comprising amagnetic element, two

controlling windings for said element, one

adapted to normally hold said element in its restrained position and theother winding adapted to render incll'ectivo the effect of the firstwinding under certain conditions and thereby effect the movement of saidelement, and means depending upon the movement of said switch for movingsaid mass to its normally restrained position.

In testimony whereof I ailix my signature in presence of two witnesses.

HARRY VVAltl) LEONARD. Witnesses B. E. SMr'rim, C. J. CORNELL.

